Appeal planned after Dieselgate trial ruling

Lawyers representing vehicle owners in the Dieselgate trial say they intend to seek permission to appeal directly from the Court of Appeal after being refused permission to appeal by the trial judge. The summary ruling was verbally delivered by Lady Justice Cockerill, who presided over the 13-week Dieselgate trial, on the second day of a two-day High Court hearing from 7-8 October 2026. The judge told the court that she will set out her reasoning in full for her decision in writing at a later date.

Following the ruling, lawyers representing the 1.6 million motorists bringing a Dieselgate claim in England and Wales said they now intend to seek permission to appeal directly from the Court of Appeal. The trial judgment, which was handed down on 10 July, ruled that just three of the 20 vehicles examined during the trial contained so-called Prohibited Defeat Devices (PDDs) - technology designed to reduce the cars' emissions under test conditions compared to when driven on the road. The three vehicles found to have contained PDDs at the trial include one Mercedes and two Peugeot/Citroen models. The other 17 vehicles, manufactured by Mercedes, Peugeot/Citroen, Ford, Renault and Nissan, were found to contain devices that did not meet the court’s definition of a PDD and therefore did not breach emissions regulations.

Lawyers for the vehicle owners had argued that the judgment created a significant divergence between the legal position in England and Wales compared with much of Europe. This is because the court decided post-Brexit not to follow several key decisions of the Grand Chamber of the Court of Justice of the European Union (CJEU), meaning defeat devices likely to be unlawful in the EU are currently permitted in England and Wales. Leigh Day’s senior partner Martyn Day said “While we are obviously disappointed with the decision, this is far from the end of the road for the 1.6 million clients bringing a legal claim over Dieselgate. In our view, the trial judgment was based on an overly narrow definition of what constitutes a Prohibited Defeat Device, and we think some of the relevant technical evidence needs to be looked at again. We believe the judgment contradicts EU law and intend to seek permission to appeal directly at the Court of Appeal to ensure that these issues are thoroughly re-examined."

Pogust Goodhead’s lead partner for the Pan-Nox case Anna Varga said “We are disappointed that permission to appeal has not been granted by the High Court. The July judgment raises important questions about the interpretation of the Emissions Regulation and the significant divergence between the position in England and Wales and that across much of Europe. These are matters of public interest. The Court itself recognised that, if its interpretation is ultimately found to be wrong, the majority of the sample vehicles would contain prohibited defeat devices based on its own contingent findings. Our responsibility to our clients remains unchanged, and we will continue to protect their interests and intend to pursue the legal avenues available to them, including seeking permission from the Court of Appeal.”